The reconstruction of microcalcification clusters in digital breast tomosynthesis

We present a novel method for the detection and reconstruction in 3D of microcalcifications in digital breast tomosynthesis (DBT) image sets. From a list of microcalcification candidate regions (that is, real microcalcification points or noise points) found in each DBT projection, our method: (1) finds the set of corresponding points of a microcalcification in all the other projections; (2) locates its 3D position in the breast; (3) highlights noise points; and (4) identifies the failure of microcalcification detection in one or more projections, in which case the method predicts the image locations of the microcalcification in the images in which they are missed. From the geometry of the DBT acquisition system, an "epipolar curve" is derived for the 2D positions a microcalcification in each projection generated at different angular positions. Each epipolar curve represents a single microcalcification point in the breast. By examining the n projections of m microcalcifications in DBT, one expects ideally m epipolar curves each comprising n points. Since each microcalcification point is at a different 3D position, each epipolar curve will be at a different position in the same 2D coordinate system. By plotting all the microcalcification candidates in the same 2D plane simultaneously, one can easily extract a representation of the number of microcalcification points in the breast (number of epipolar curves) and their 3D positions, the noise points detected (isolated points not forming any epipolar curve) and microcalcification points missed in some projections (epipolar curves with less than n points).